every project involving construction of number of flats not exceeding 8 shall be exempted irrespective of area of the land. Every project involving development of land having area not exceeding 500 sq. meters into plots for sale shall be exempted.
2) in your case since it is having only 8 flats and area of plot is under 500 square meters builder would be exempted from RERA
3) You can seek clarification in this regard from BBMP as to whether OC is not required for construction of 8 flats